1. Field of the Invention
The present invention relates to electronic equipment suitable for use in personal computers and the like and particularly to a system for monitoring the residual energy of a battery in a battery-powered device.
2. Technical Background
Recently, notebook type battery-powered personal computers have been developed in the field of small-sized electronic equipment. When the battery power is consumed in such a device during operation, it will lead to serious problems in that the programs and data are destroyed. To avoid such serious problems, means for monitoring the residual power of the battery is required. The prior art has proposed a method of providing a battery monitoring program stored in the device itself to monitor the operation of the device while calculating the residual energy, or charge, of the battery at all times. However, it was difficult for such a battery monitoring program to indicate the residual energy of the battery in real time.
In equipment having a substantially constant current consumption such as a battery-powered razor, the residual energy of the battery can be calculated and indicated by a microcomputer mounted in the interior of a battery pack and adapted to detect the flow of electric current. In another type of equipment having a current consumption which is variable over a large range (e.g. a range between 100 milliamperes and several amperes) such as a notebook type personal computer, the electric current can not accurately be measured throughout its operational range even if it includes such a microcomputer as described above.